A student was given a standard Fe(s) | Fe 2+ (aq) half-cell and another halfcell containing an unknown metal M immersed in 1 M MNO3(aq).

A student was given a standardFe(s) | Fe2+(aq) half-cell and another halfcell containing an unknown metal M immersed in 1 M MNO3(aq). When these twohalf-cells were connected at 25◦C, the complete cell functioned as a galvanic cell withE = 1.24 V. The reaction was allowed to continue overnight and the two electrodes wereweighted. The iron electrode was found to belighter and the unknown metal electrode washeavier. What is the standard potential ofthe unknown M+/M couple?